Guidance and Control - Review

Beginning with a report on the ASTP docking
targets, Legostayev indicated that the primary target had been
mounted on Soyuz and its proper alignment had been verified by Soviet
and American specialists during the joint preparations at Baykonur
during May. These checkout procedures involved the use of an
American-designed fixture mounted on the face of the Soviet docking
gear. A contingency target made from three fixed metal plates was
also installed on Soyuz, in case the folded primary target failed to
erect. In either event, the Apollo commander would have a target on
which to sight during the final phase of docking.13 After discussing the orientation lights and the
optical tracking hardware, Legostayev turned to the subject of
control systems.

The Soviet Working Group 2 chairman noted that
extensive studies had been made of the control system from
operational and safety standpoints.

Docking target alignment
fixture.

[293] The joint team had
agreed to two major limitations on the use of the Apollo control
system. First, to prevent undue stress from being placed on the Soyuz
solar panels, the American agreed to use only two of the four roll
jets to rotate the spacecraft during the docked phase of the flight.
The second agreed restriction had to do with shutting down the Apollo
forward-firing reaction control system (RCS) engines. As agreed
during the final meeting in Houston, to protect Soyuz from, the RCS
plume, the forward-firing engines would be shut off within 2 seconds
after docking system capture. No forward firing would be allowed
during the docked part of the flight operations.14

The basic safety of the Apollo and Soyuz
propulsion and control systems was documented in reports on each
spacecraft, which provided a functional description of those systems
and of how they operated. The Soviet and American specialists
concluded that the control and propulsion systems of both spacecraft
operated in a non-hazardous manner and posed no dangers to the crews
during docked operations. Finally, Legostayev told the FRR Board that
there were no outstanding issues; from Group 2's point of view all
was in readiness for the flight.15 After a few quick questions from John Yardley and
Academician Petrov, the FRR attendees adjourned for lunch.

15. Ibid., p. WG-2-21.
The results of the safety assessments were presented in two
documents: "ASTP Safety Assessment Report for Apollo Propulsion and
Control Systems," ASTP 20 102, 3 May 1974, and "ASTP Safety
Assessment Report for Soyuz Propulsion and Control Systems," ASTP 20
202.1, 1 May 1975. Soviet comments on guidance and control are
contained in V. P. Legostayev, "Korabli idut na sblizhenie"
[Spacecraft are approaching each other], in Soyuz i Apollon, pp.
100-115. The author emphasizes the superior automatic (or
ground-controlled) guidance systems of the Soyuz and the changes that
the Soviets had to make in their spacecraft to accommodate the Apollo
systems and configuration incompatibilities.